vt.

1. 使恼怒；使烦躁
   His letter irritated me a little.

   他的信使我有点恼火。

2. 使过敏；使难受；使发炎；使疼痛
   These tight shoes irritate my toes.

   我的鞋太紧，夹痛我的脚趾。

3. 刺激，使兴奋

vi.

1. 引起恼怒；引起不愉快

v.

1. make annoyed or angry.
2. cause inflammation in (a part of the body).
3. Biology  stimulate (an organism, cell, etc.) to produce an active response.